| The reinforced concrete column-concrete lattice beam structure system is a new type of structural system.The column net is square,the column spacing is 12~21m,and the prestressed concrete beams with column support and spacing of about 3m are enclosed as the floor and frame columns.There may or may not be beams bet ween the beams,but all the beams in the open space are of the same section height,and the conventional beam-spans with a span of 3~4m and a thickness of 100~120mm are formed.The space enclosed by the beam at the top of the frame column is filled to form a solid slab with the same height as the beam,and the entire floor is flat.From the structural form,the system is similar to the slab-column structure.Compared with the slab-column structure system,the floor span of the building is large,the structure has a small weight,and the amount of materials is small.Under the action of earthquake,the structural system has the problems of poor seismic performance,small lateral stiffness and lateral bearing capacity,and the nodes are prone to damage.Based on the above reasons,this paper proposes an improvement measure to change the reinforced concrete column into a concrete-filled steel tubular column.The beam still uses reinforced concrete girder,column cap thick plate and short steel beam at the joint.The short steel beam is built into the thick plate of the column cap and welded with the concrete filled steel tube column.The improved system is called the concrete filled steel tube column-concrete lattice beam structure system.There are quite a few researches and applications related to this new structural system.In this paper,the large-scale general finite element software Abaqus 6.14 is used to analyze the elastic and elastoplasticity of the new structure,including the following work:(1)Establish a single-layer 1×1 span finite element model of a new type of concrete-filled steel tubular column-concrete lattice beam,and establish a finite element model of reinforced concrete column-concrete lattice structure(hereinafter referred to as the whole concrete structure)as a comparison.The elastic analysis of different load conditions under load is used to analyze the deflection,stress and crack distribution under vertical load.The results show that the main compressive stress shows that the new structure and the weak part of the whole concrete structure are at the junction of the grid beam and the thick cap of the column cap.It can be known from the Mises stress that the new structure and the stress of the whole concrete structure mainly occur at the joints of the column caps,and the stress distribution is relatively dispersed.Under the same vertical load,the maximum vertical displacement of the new structure is smaller than that of the whole concrete structure,which indicates that the new structure has better stiffness and deformation ability.It can be seen from the crack distribution that the pre-stress can make the structure not crack under normal use conditions.(2)According to the requirements of relevant regulations such as "Concrete-tube Concrete Structure"(06SG524:2006),a new type of CFST-reinforced concrete beam joints was designed,and the nodes of the whole concrete structure were established for comparative analysis.The Abaqus was used to simulate the reciprocating load,and the whole process of the failure was analyzed under the monotonic loading.The results show that the plastic hinge of the new node appears at the beam end,and the column cap thick plate node basically has no damage.It conforms to the design principle of strong columns and weak joint members.At the same time,the effects of axial compression ratio and prestressing parameters on the seismic performance of the joints are studied.(3)Establish a new one-frame finite element model with one span and two layers,a nd establish a single-span two-story finite element model of the whole concrete structure as a comparison,perform PUSHOVER analysis,load with inverted triangular load,adopt arc Long-term analysis and calculation,with the structural carrying capacity fa lling to 85% of the peak carrying capacity as a sign of the end of the push.The results show that under the displacement points of small earthquakes,medium earthquakes and large earthquakes,the structure is kept in elastic state for the new structure,the steel pipe is not yielded,and the concrete is not crushed.Good seismic performance.For the entire concrete frame,the structure enters the plastic phase under the action of large earthquakes.At the same time,according to the target displacement point and the nappe load-displacement curve of the two structures at different seismic levels,the distribution of structural displacement along the height and the displacement angle of the interlayer under different seismic levels are obtained.The horizontal deformation distribution of the structure is relatively uniform and meets the requirements.The displacement angle between the layers under the small earthquake is limited to 1/550,the displacement angle between the lower earthquakes is limited to 1/200,and the displacement angle between the two earthquakes is limited to 1/50.It can be seen that the seismic performance of the two structures meets the requirements,achieving “small earthquakes”.Three-Performance Seismic Design Performance Level Design Principles: Not Bad,Medium Shock,and Big Earthquake(4)The finite element model of a single-span two-story finite element model and the one-span two-story finite element model of the whole concrete structure are used to analyze the dynamic elastoplastic time history.Elcentro wave,Taft wave and artificial are carried out on the two structures.Elastoplastic process response analysis under wave action.At the same time,the dynamic structure time-history analysis based on vibration mode superposition is carried out to compare the new structure.The results show that the maximum interlayer displacement and the maximum interlayer displacement angle of the two structures appear in the first layer under the action of three kinds of seismic waves,and are far less than the norm limit.There is no obvious weak layer;the inter-layer relative displacement and interlayer displacement angle of the whole concrete structure are larger than the new structure.The new structure is characterized by multiple earthquakes or rare earthquakes.The section steels of the thick-plate joints of the column caps and the longitudinal ribs of the grid-beams are in elastic working state,and the tensile damage at the junction of the thick-plate and the grid-beam of the column cap is serious.The goal of a weak node weak component.The structure of the whole concrete structure is in elastic state under the action of multiple earthquakes.Under the rare earthquake,the structure enters the plastic state,the longitudinal reinforcement o f the lattice beam and the longitudinal reinforcement of the reinforced concrete column yield,and the reinforced concrete columns,concrete lattice beams and concrete slabs are subjected to Serious damage... |
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